Complex trinuclear metal salts

ABSTRACT

Complex trinuclear metal salts, methods for the production of these salts by reaction of salts of aluminum or of aluminum and trivalent chromium, which contain monovalent anions, with acrylic acid and the amount of an alkaline reacting agent necessary for their neutralization or with salts or acrylic acid and a method of tanning using these metal salts.

United States Patent Erdmann et al.

1 1 Jan. 30, 1973 i541 COM FLEX TRINUCLEAR METAL SALTS [75] Inventors:Hans Erdmann, Heidelberg; Franz Friedrich Miller, Ludwigshafen, both ofGermany [73] Assignee: Badische Anilin 8: Soda FabrikAktiengesellschaft, Ludwigshafen/R- hine and Rhineland-Pfalz, Germany[22] Filed: Sept. 3, 1970 [2i] Appl. No.: 69,461

[52] US. Cl. ..260/438.5 R, 8/9426, 260/448 R [51] Int. Cl. ..C07f 11/00{58] Field of Search ..260/438.5 R, 448 R [56] References Cited UNITEDSTATES PATENTS 2,9l8 483 l2/l959 Varul .260/4385 C 395L748 8/1962 DePree et al. ..260/438.5 R X 3,493,318 2/l970 Chain et al ..260/438.5 R3,576.762 4/l97l Francoise et al ..260/438.5 R

FOREIGN PATENTS OR APPLICATIONS 2,013,064 3/1970 France 260/4385 RPrimary Examiner-H. Sneed Atrorney.lohnston, Root, O'Keefe, Keil,Thompson & Shurtleff [57] ABSTRACT Complex trinuclear metal salts,methods for the production of these salts by reaction of salts ofaluminum or of aluminum and trivalent chromium, which contain monovalentanions, with acrylic acid and the amount of an.'alkaline reacting agentnecessary for their neutralization or with salts or acrylic acid and amethod of tanning using these metal salts.

12 Claims, No Drawings COMPLEX TRINUCLEAR METAL SALTS The presentinvention relates to new salts which contain aluminum or aluminum andtrivalent chromium as central atoms in a trinuclear complex cation, andacrylic acid anions as acido groups with or without hydroxo groups. Theinvention also relates to a tanning method using these complextrinuclear metal salts.

Similar complex trinuclear metal salts but with low saturated fattyacids (formic acid, acetic acid or propionic acid) have been proposedfor aluminum as the central atom in Belgian Pat. No. 737,935 and foraluminum and trivalent chromium as central atoms in Belgian Pat. No.736,165.

lt is an object of the invention to provide tanning salts which cause ahigh shrinkage temperature and consequently improve the handle andflexibility of the leather obtained. Leather which is able to withstandthe boilingtest is obtained with these tanning salts. A particularlygood property is that unsaturated carboxylic acids contained in thecomplex can be polymerized in the leather for example by means of redoxsystems. As a result there is the advantage that the leather hasincreased fulness and waterproofness in use and there is also thepossibility in the subsequent ironing of the leather of carrying out thefinishing without an additional operation.

The new salts are characterized by a cation having the general formula:

where M denotes aluminum and M denotes trivalent chromium, R denotes theradical of acrylic acid combined twice between two metal atoms, adenotes an integer from 1 to 3 and m denotes an integer from 2 to 6.

When a denotes the integer 3, pure complex trinuclear aluminum salts areobtained; when a denotes 2 or 1, mixed salts of aluminum and chromiumare obtained.

The new aluminum or aluminum/chromic complex salts may contain anymonovalent anions provided they do not make the complex insoluble inwater, for example chloride, bromide, iodide, perchlorate, nitrate,formate, acetate and propionate ions. The complex salts according to theinvention preferably contain chloride ions.

The aluminum complex salts have a structure in which, between the threecentral atoms, a total of six acido and hydroxyl groups, and at the twoexternal metal atoms, three aquo groups in each case are coordinativelycombined:

R denotes the acido radical of acrylic acid and A denotes a monovalentanion from the group given above.

The formula represents the p-hexacido-hexaquotrL aluminum salt(A1,R,(H,O),)A,. Up to four of the acido groups in the formula may bereplaced by hydroxyl groups. I

Aluminum/chromic complex salts in which one or two aluminum atoms arereplaced by trivalent chromium atoms have the same structure, as forexample p.-

tetracido-u-dihydroxo-hexaquo-monoaluminumdichromic chloride:

The following are given as further trialuminum, dialuminum-monochromicor monoaluminum-dichromic complex salts having the same structure:

Complex salts according to the invention may be prepared in variousways. For example aluminum salts of monobasic acids alone or togetherwith appropriate chromic salts in the molar ratio of chromium toaluminum given by the formula may be dissolved in water, and monomericacrylic acid with an equivalent amount of an alkaline reacting agent, orthe alkali metal salt of this acid, added in such an amount that atleast 0.67 carboxylic acid radical and not more than 1.33 hydroxylgroups are available for each metal atom. The sum of the number ofacrylic acid radicals and that of the hydroxyl groups should amount to2.0 per metal. After the reaction is over, the complex salts formed maybe processed into powder in a spray-dryer.

The sequence in which the said starting materials are brought togetheris not important. Thus it is immaterial for the production of saltsaccording to the invention whether a start is made from solutions of themetal salts in acrylic acid while maintaining the above molarproportions or whether acrylic acid in the form of its alkali metalsalts with or without alkaline reacting agents is added to metal saltsof other monobasic acids or whether solutions of basic metal salts aretreated with free acrylic acid. The setting up of the abovementionedmolar ratios in the molecule is the decisive factor.

lncreasing the proportion of acrylic esters in the form of the alkalimetal salts per metal atom beyond the value 2 does not affect theformation of trimetal salts, but in this case water-insoluble productsare obtained with the pure trialuminum salts devoid of chromium. Theexcess may cause an exchange of mineral acid anions of the trimetal saltfor carboxylic acid anions or take no further part in the reaction withthe present complex salts.

Adding alkali to a trimetal salt already occupied by acido groups causesa removal of the acido groups. An increase of the proportion of hydroxylgroups beyond the amount of 1.33 hydroxyl groups per mole of metal,however, results in precipitation. Conversely all the hydroxyl groups ina trimetal salt previously proportionately basified by adding alkali canbe replaced by acido groups by the addition of free acrylic acid.

The alkaline reacting agents may be not only oxides and hydroxides ofalkali metals and alkaline earth metals but also their carbonates.Examples are sodium hydroxide, potassium hydroxide, sodium carbonate,sodium bicarbonate, calcium hydroxide, calcium carbonate, magnesiumcarbonate and dolomite.

The aluminum complex salts described herein are colorless. Mixedcomplexes of aluminum and trivalent chromium are pale green in powderedform, but greenish blue to ink blue in solution.

Salts according to the invention having the above formulas areoutstandingly suitable for tanning. They have the advantage over priorart aluminum salts used for tanning that they are more resistant tohydrolysis. Therefore the material tanned therewith has a highershrinkage temperature of 78 to 80 C, a great fullness and highsuppleness of handle. Complex salts prepared with trivalent chromiumgive pale, light blue leather which withstands the boiling test.

These advantages are particularly valuable when salts according to theinvention are used for tanning pelts which have been pretreated withaldehydes or agents yielding aldehydes. Aldehydes include especiallyformaldehyde, acetaldehyde, propionaldehyde, glyoxal and glutaraldehyde.Substances which split off aldehydes under the conditions of tanning maybe used instead of the aldehydes or together with the same. Theseinclude sodium hydroxylmethanesulfonate, hexamethylenetetramine,paraformaldehyde, paraldehyde, metaldehyde and particularly N-methylolcompounds, for example thos of urea, cyclic urea derivatives, melamineand dicyanodiamide. It has proved suitable to use the aldehydes inamounts of from 0.5 to 3%, preferably 1 to 1.5%, with reference to theweight of the material being tanned. Agents releasing aldehydes areadvantageously used in amounts equivalent to the said amount of aldehydeor to the equivalent amount of aldehyde split off based in theequilibrium condition in solution.

Thus for example the pretreatment of pelts with 3% formaldehyde not onlyimproves the handle properties of the finished leather and prevents thealuminum in the tan being washed out but also increases the shrinkagetemperature to 88 to 90 C.

It is possible to prevent the acrylic acid radicals from being washedout by treating the leather obtained with a prior art redox system, forexample persulfate/sulfite, and thereby polymerizing the acrylic ormethacrylic acid radicals. Fullness and waterproofness of the leatherare enhanced by this measure.

It has proved to be very convenient to use the salts according to thisinvention in amounts which are equivalent to 2.5 to 4% of Al,0, (or A1and C50,) based on the weight of pelts being tanned. In other respects,the same tanning conditions may be used with the salts according to theinvention as are used with other aluminum tans. It has proved to beparticularly advantageous to buffer the tanning liquor with alkalinereacting agents to a pH value of about 5 towards the end of the tanning.

The following Examples illustrate the invention. The parts andpercentages specified in the Examples are by weight. Percentages byweight in the tan recipe relate to the weight of the pelts being tannedunless otherwise stated.

EXAMPLE 1 p.triacrylatotri-;t-hydroxo-hexaquo-trialuminum chloridehaving the formula:

72 parts of monomeric acrylic acid is added to a solution of 226 partsof a 66% basic aluminum chloride (22% of A1 0 in 100 parts of water andthe aged solu tion is spray-dried into a powder.

The product obtained in this way is a colorless powder having very goodsolubility in water. It contains an amount of sodium chlorideoriginating from the reaction of aluminum chloride, in addition to thesalt according to the invention.

The complex salt thus obtained is used for tanning cowhides according tothe following specification:

Completely delimed and bated pelts are treated in 100% of aqueous liquorcontaining 10% of sodium chloride and 3% of 30% aqueous formaldehydesolution. Thirty minutes later 15% of triacrylato-trihydroxo-trialuminumchloride is added as a powder and after a period of 6 hours the whole isbuffered to a pH value of 5.0 with about 5% of sodium bicarbonate in anumber of portions. Total treatment time is about 8 to 10 hours. Then 1%of persulfuric acid/sulfite is added and the pH value of the liquor iscorrected again to 5.0 after one hour. After having been kept on thehorse overnight the hides are fatliquored with 2 to 5% or pure fat inthe form of a commercial cationic fatliquor in a 100% liquor at 50 C.Drying, sawdusting and staking are carried out as usual.

Leather prepared in this way is white, has a shrinkage temperature of 88C, is full and supple in handle and contains the aluminum tan includingthe acrylic acid in a form incapable of being be washed out.

EXAMPLE 2 Hexacrylato-hexaquo-dialuminum-monochromic chloride having theformula:

A solution of 144 parts of acrylic acid and 106 parts of sodiumcarbonate in 4,800 parts of water is added to a solution of 161 parts ofaluminum chloride (AlCl -61-l 0) and 89 parts of chromic chloride (CrCl'fl O) in 200 parts of water while stirring. The aged solution isspray-dried.

A white-green powder is obtained which dissolves well in water with agreen color. In addition to sodium chloride and sodium acrylate itcontains a salt having the formula:

It may be used as in Example 1 for tanning, with or without pretreatmentwith formaldehyde. Leather is obtained which withstands the boilingtest, has a pale blue color and contains aluminum and acrylic acidradicals in a form incapable of being washed out.

EXAMPLE 3p-tetracrylato-p.-dihydroxo-hexaquo-dichromicmonoaluminum-chloridehavingthe formula:

A solution of 106 parts of sodium carbonate in 1,000 parts of water isadded to a solution of 178 parts of chromic chloride (CrCl '6H,O) andparts of aluminum chloride (AlCl,-6H,O) in 200 parts of water whilestirring and the stirring is continued until the solution is clear. Then96 parts of monomeric acrylic acid is added. The aged solution isspray-dried.

A green powder is obtained which dissolves in water with a blue color.In addition to sodium chloride it contains a salt having the formula:

1t may be used as in Example 1 for tanning with or without pretreatmentwith formaldehyde. A grey leather is obtained which contains chromiumand aluminum as well as the acrylic acid radicals present in a formincapable ofbeing washed out.

EXAMPLE 4 u-hexacrylato-hexaquo-trialuminum chloride having the formula:

86.5 parts of monomeric acrylic acid is added to a solution of 136 partsof a commercial 66% basic aluminum chloride ([Al(OHMCl-l-ZNaCl) having acontent of 22% A1 0 in 300 parts of water and the whole is made up to1000 parts with water. The aged solution is spray-dried.

A white powder is obtained which gives a colorless solution in water. Itmay be used for tanning as in Example 1.

EXAMPLE 1 u-diacrylam-p.-tetrahydroxo-hexaquo-trialuminum chloridehaving the formula:

28.8 parts of monomeric acrylic acid is added to a solution of 136 partsof a commercial 66% basic aluminum chloride ([Al(OH) ,+2NaCl) having acontent of 22% of A1 0 in 300 parts of water and the whole is made up to1000 parts with water. The aged solution is spray-dried.

A white powder is obtained which gives a colorless solution in water. Itmay be used as in Example 1 for tanning pelts or after-tanning chromeleather.

EXAMPLE 6 u-triacrylato-p.-trihydroxo-hexaquo-dialuminummonochromicchloride having the formula:

A mixture of 43.2 parts of monomeric acrylic acid and 33.6 parts ofsodium bicarbonate in 500 parts of water is added to a solution of 90.4parts of a commercial 66% basic aluminum chloride ([Al(OH C|+2NaCl)having a content of 22% of Al,0 and 53.3 parts of chromic chloride (CrCl'6H,O) in 300 parts of water and-the whole is made up to 1000 parts withwater. A blue violet solution is obtained. By spray-drying a green saltis formed which dissolves in water with a green color. It containssodium chloride as well as the salt according to the invention.

EXAMPLE 7 u-hexacrylato-hexaquo-monoaluminum-dichromic chloride havingthe formula:

A mixture of 86.5 parts of monomeric acrylic acid and 101 parts ofsodium bicarbonate in 500 parts of water is added to a solution of 48.2parts of aluminum chloride (AlCl 'H O) and 106.6 parts of chromicchloride (CrCl '6l-l O) in 300 parts of water, and the whole is made upto 1,000 parts with water. A red violet solution is obtained whichchanges to green in a few weeks. By spray-drying the red violet-solutiona green salt is obtained which dissolves in water to give a greensolution. it contains sodium chloride in addition to the salt accordingto the invention.

EXAMPLE 8 u-diacrylato-p.-tetrahydroxo-hexaquo-monoaluminum-dichromicchloride having the formula:

A mixture of 28.8 parts of monomeric acrylic acid and 67.0 parts ofsodium bicarbonate in 500 parts of water is added to a solution of 45.2parts of a commercial 66% basic aluminum chloride ([Al(OH) ]Cl ZNaCl)having an A1 0 content of 22% and 106.6 parts of chromic chloride (CrCl-6l-1,O) in 300 parts of water and the whole is made up to 1000 partswith water. An ink blue solution is obtained. By spray-drying a bluegreen salt is obtained which gives a dark blue solution in water. It maybe used for tanning as in Example 1.

We claim:

1. A complex trinuclear metal salt whose cation has the formula where Mdenotes aluminum and M denotes trivalent chromium as the central atoms,R denotes the radical of acrylic acid twice combined between two metalatoms, a denotes an integer from 1 to 3 and m denotes an integer from 2to 6 and which contains monovalent anions which do not make the complexmetal salt insoluble, which anions are selected from the groupconsisting of chloride, bromide, iodide, perchlorate, nitrate,formate,acetate and propionate ions.

2. A complex trinuclear metal salt as claimed in claim 1 in which a inthe formula of the cation denotes one of the integers 1 and 2.

3. A complex trinuclear metal salt as claimed in claim 2 which containschloride ions as the monovalent anions.

4. A complex trinuclear metal salt whose cation has the formula Rdenotes the radical of acrylic acid combined twice between two metalatoms, and m denotes one of the integers from 2 to 6, and which containsanions which do not make the complex 'metal salt insoluble, which anionsare selected from the group consisting of chloride, bromide, iodide,perchlorate, nitrate, formate, acetate and propionate ions.

5. A complex trinuclear metal salt as claimed in claim 4 which containschloride ions as the monovalent anions.

fig? UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,7 ,211 Dated January 30, 1973 Inventor) Hans Erdmann and FranzFriedrich Miller It is certified that error appears in theabove-identified patent: and that said Letters Patent are herebycorrected as shown below:

Cover page, left hand column, insert 7 p Foreign Application PriorityData September 5, 1969 Germany P 19 45 006.7

Column 2, line 12, [A;L R (0H)( H20) 3 A should read V Column line 39,I, H)z1 .+iNacn should read )2] c1 2Nac1) Signed and sealed this 9th dayof October 1973.

(SEAL) Attest:

EDWARD M.PLETCHER,JR. RENE D; TEGTMEYER Attesting Officer ActingCommissioner of Patents

1. A complex trinuclear metal salt whose cation has the formula (Ma1 M(3a)2 Rm(OH)(6 m)(H2O)6) ( )( )( ) where M1 denotes aluminum and M2denotes trivalent chromium as the central atoms, R denotes the radicalof acrylic acid twice combined between two metal atoms, a denotes aninteger from 1 to 3 and m denotes an integer from 2 to 6 and whichcontains monovalent anions which do not make the complex metal saltinsoluble, which anions are selected from the group consisting ofchloride, bromide, iodide, perchlorate, nitrate, formate, acetate andpropionate ions.
 2. A complex trinuclear metal salt as claimed In claim1 in which a in the formula of the cation denotes one of the integers 1and
 2. 3. A complex trinuclear metal salt as claimed in claim 2 whichcontains chloride ions as the monovalent anions.
 4. A complex trinuclearmetal salt whose cation has the formula (Al3Rm(OH)(6 m) (H2O)6) ( )( )() R denotes the radical of acrylic acid combined twice between two metalatoms, and m denotes one of the integers from 2 to 6, and which containsanions which do not make the complex metal salt insoluble, which anionsare selected from the group consisting of chloride, bromide, iodide,perchlorate, nitrate, formate, acetate and propionate ions.
 5. A complextrinuclear metal salt as claimed in claim 4 which contains chloride ionsas the monovalent anions.
 6. (Al2Cr(H2C CH-COO)6(H2O)6)Cl3. 7.(AlCr2(H2C CH-COO)4(OH)2(H2O)6)Cl3.
 8. (Al2Cr(H2CCH-COO)3(OH)3(2O)6)Cl3.
 9. (AlCr2(H2C CH-COO)6(H2O)6)Cl3.
 10. (AlCr2(H2CCH-COO)2(OH)4(H2O)6)Cl3.
 11. (Al3(H2C CH-COO)3(OH)3(H2O)6)Cl3.